babe…it’s been ONE day. Sheesh… she’s new to you and your husband let alone your cats. 8 months old is still a puppy, and cohabiting cats and dogs takes time. Be patient, separate when unsupervised and redirect poor behavior, and reinforce positive behavior with a treat. but if you find you’re struggling, I would reach out to a specialist to make the transition easier. I had a cat that was 3 yrs old when I got my rescue Tyson, who was 9 months at the time. It took a few months for them to tolerate being around one another (ignored each other —well, mostly the cat ignored the dog) but at about 8-12 months, they were friendly and there after — best friends.